This invention relates to software editors, and more particularly to systems for editing semiconductor-process recipes from different semiconductor-processing machines.
Advances in semiconductor manufacturing are the driving force behind increases in productivity in almost all areas of today""s economy. Powerful computers and networks rely on inexpensive semiconductor integrated circuits or chips. Semiconductors are mass produced as batches of silicon wafers move through various steps of a semiconductor fabrication plant or xe2x80x98fabxe2x80x99. Each wafer may contain hundreds or thousands of individual chips.
A batch of wafers is processed by a sequence of various process steps. Furnaces are used to grow silicon-dioxide (oxide) layers on the silicon surface of the wafers. Steppers and other photolithography machines expose a layer of photo-resist on the wafer surface, while chemical baths wash away either the exposed or un-exposed photo-resist to form circuit and device patterns on the wafer. Low-pressure plasma-gas etchers cut into oxide or other layers patterned on the wafer. Chemical-vapor-deposition (CVD) machines and metal-vapor deposition machines deposit thin yet uniform layers on the wafer. Ion implanters drive high-energy beams of ions into the wafer, forming doped regions. Wafers processed in a fab also undergo various tests and measurements for durability, defects, and conformance with original design and process requirements. Various wafer inspection, metrology, test, and measurements tools are used.
Each of these semiconductor-processing, inspection, metrology, and measurement machines requires a set of operating instructions (a processing program) or a xe2x80x9crecipexe2x80x9d. The recipe varies for each kind of machine, and even among different machine manufacturers for the same kind of machine. For example, an etch system by Applied Materials of Santa Clara, Calif. may require a 10-minute reaction time with a certain flow of gases, while the reaction chamber is kept at a certain elevated temperature. At the end of the 10-minute reaction time, the flow of reactive gasses are gradually reduced and replaced with inert gasses as the temperature is lowered. Another etch system by Lam Research of Fremont, Calif. may require a 15-minute reaction time, with a different mixture of gasses and a different temperature.
Other kinds of semiconductor-processing equipment require vastly different recipes. A furnace recipe may specify how rapidly a tray of wafers is pushed into the furnace tube while inert gas is pumped through the furnace. Then the temperature is raised to a first target. Next a reactive gas such as oxygen or silane is pumped through the furnace tube to form an oxide or poly-silicon layer. Finally some nitrogen or nitrogen-oxide may be introduced to form a capping layer of a nitride over the oxide or polysilicon. Then after a specified time, inert gas is pumped through the furnace as it cools down to a second target temperature over a specified time interval. Finally the tray of wafers are pulled out of the furnace tube at a specified rate and allowed to cool before being moved to the next process machine.
These recipes can become quite complex and varied as process engineers attempt to tweak the process for desired electrical and manufacturing-yield results. Different semiconductor products may require different recipes or combinations of steps. A dynamic-RAM process may require lighter ion-implant doses than a process for logic chips. Different oxide thicknesses require different reaction times in the furnaces.
Wide Variety of Semiconductor-Process Equipmentxe2x80x94FIG. 1
FIG. 1 illustrates some of the semiconductor-process equipment in a wafer-fab clean room. Semiconductor-manufacturing equipment 10 includes low-pressure and plasma reaction chambers, lithography equipment, ion implanters, wafer wash stations, and furnaces, among others. Each piece of equipment 10 typically includes an embedded computer or controller for operating the equipment. The embedded computer controls reaction times, gas flow rates, temperatures, ion-implant doses and energy, and perhaps robotic movement of wafers through the equipment""s reaction chambers. A video display may be included to alert equipment operators when steps have completed, and keyboards allow the operators to select recipes for use with a current batch of wafers. Bar-code readers may also be used as an input device, reading a bar code on each box of wafers.
Each of the different pieces of semiconductor-manufacturing equipment 10 has a different user interface, requiring special training for the operators and process engineers. Few if any engineers can operate all equipment in a fab, requiring that process engineers specialize in one or a few types of semiconductor-manufacturing equipment. Some machines may provide recipe-editing and display features, allowing a process engineer to view and edit a recipe, and manage many different recipes on the embedded computer""s storage. However, the lack of a standard user interface among the different machines limits an engineer to editing recipes on just a few of the many machines.
Other kinds of factories have established file standards. See U.S. Pat. Nos. 5,828,851 and 5,838,563. Unfortunately, the extremely competitive environment for semiconductor-manufacturing equipment has prevented adoption of such standards. Instead, separate workstation computers are often used in the fab in conjunction with each process station. See U.S. Pat. Nos. 5,432,702 and 5,105,362.
While such recipe editing is useful, the editing feature of semiconductor-manufacturing equipment has been called the world""s most expensive word processor. Semiconductor-manufacturing equipment can cost as much as a million dollars per machine. Use of the editing features may prevent the semiconductor-manufacturing equipment from processing wafers. This down-time is quite expensive in terms of lost wafer revenue and depreciation of the equipment. Thus is it very undesirable to edit recipes on the semiconductor-manufacturing equipment itself.
The semiconductor-manufacturing equipment is usually located inside a low-particle-density environment called a clean room. To maintain the low particle density, all persons are required to wear special clothing known as a xe2x80x98bunny suitxe2x80x99. Gloves, masks, and even breathing filters are required in some clean rooms. Typing in a recipe while wearing gloves is cumbersome, and engineers sometimes may be tempted to remove the gloves, generating particles in the clean room.
Offline Editing on a PCxe2x80x94FIG. 2
FIG. 2 shows transferring a recipe from a clean room to a personal computer (PC). Since editing a recipe on the semiconductor-manufacturing equipment (on-line editing) is so expensive, recipes are often copied to a diskette and edited on a PC (off-line editing). Semiconductor-manufacturing equipment 10 is located in a clean-room fab and is almost continuously used for manufacturing operations. Little time on equipment 10 is available for use by the process engineer.
Semiconductor-manufacturing equipment 10 has a user interface, allowing recipes to be edited on the machine. An engineer could type in a recipe on keyboard 12 and view recipes on video display 14, but it is more convenient to copy recipes to a floppy diskette in floppy drive 16 on equipment 10. Diskette 18 can then be carried out of the clean-room fab and inserted into PC 20 at the engineer""s office. The engineer can then edit the recipes and create new recipes, using a standard text editor or a proprietary recipe editor provided by the semiconductor-manufacturing equipment manufacturer.
These recipes can be printed on the office printer 22. The new recipes can be copied to diskette 18 and then carried into the clean-room fab. The new recipes on diskette 18 can then be copied to the embedded computer in semiconductor-manufacturing equipment 10 using floppy drive 16.
Different Machines Use Different Recipe Formats, Need Different Editors
Other semiconductor-manufacturing equipment 10xe2x80x2 uses a different file format for recipes, and has different process parameters and conditions that must be set. While recipe editing could be done on semiconductor-manufacturing equipment 10xe2x80x2 itself, this may require that wafer processing stop while the editing is performed. This down-time is extremely expensive and disruptive of other fab operations.
Instead, an engineer may copy the recipe from semiconductor-manufacturing equipment 10xe2x80x2 to diskette 18xe2x80x2 and carry the diskette to his office PC 20xe2x80x2. Since semiconductor-manufacturing equipment 10xe2x80x2 is a different machine than semiconductor-manufacturing equipment 10, a different editor is used on PC 20xe2x80x2 than on PC 20. Some manufacturers of semiconductor-manufacturing equipment 10xe2x80x2 may supply an off-line recipe editor for use on PC 20xe2x80x2, but this editor cannot edit recipes from other machines, such as from semiconductor-manufacturing equipment 10. There is no universal editor for different kinds of recipes from different semiconductor-manufacturing equipment.
Some clean-room fabs now connect semiconductor-manufacturing equipment 10, 10xe2x80x2 to a network such as a local-area network (LAN). This allows the engineer at PC 20, 20xe2x80x2 to copy recipe files directly from semiconductor-manufacturing equipment 10 using the LAN. Unfortunately, the problem of differing file formats for recipe files from different semiconductor-manufacturing equipment still remains. Often binary, proprietary file formats are used for different machines.
Some of these file formats do not include adequate documentation, such as full revision histories and fields for names of engineers making process changes. Security is also important, since operators should not be able to change recipes. Even engineers in other groups should not be authorized to make recipe changes. Some recipe changes may require approval of the engineering or fab-production supervisor while other changes may be allowed. Critical parameters such as temperature should require a higher security level than less-important parameters such as furnace-tray push/pull times and wafer-handling time between two process chambers. Parameter-level security is desired in addition to security for the overall recipe.
What is desired is an off-line recipe editor for use in an office outside of the clean-room fab. It is desired to edit recipes from many kinds of different semiconductor-manufacturing equipment machines, including recipes for different kinds and makes of machines. It is desired to edit recipe files having a variety of proprietary formats using a single recipe editor. It is desired to make changes to process conditions such as temperature, reactants, gas flows and pressures, reactions and delay times, and plasma or ion-beam energies. A universal or unified recipe editor for semiconductor-manufacturing equipment is desired.
A universal semiconductor-recipe editing system has a recipe data object model (R-DOM) object model that is coupled to read and write recipe data files. Each recipe data file controls a process performed on a wafer by a semiconductor-manufacturing machine. The R-DOM object model includes a means for reading recipe data files for a variety of semiconductor-manufacturing machines from different vendors that require different native formats of the recipe data files. The R-DOM object model locates and reads a desired parameter within a recipe data file.
A visual recipe editor is coupled to the R-DOM object model. It displays parameters from the recipe data file to a user. The R-DOM object model sends the desired parameter to the visual recipe editor for display to the user.
An R-DOM file is accessed by the R-DOM object model. It identifies locations of parameters in the recipe data file. The R-DOM file contains a sequence of parameters. The sequence of parameters is in a same order as a native sequence of parameters in the recipe data file.
The R-DOM object model reads the R-DOM file to determine a location of the desired parameter in the recipe data file. The R-DOM object model reads the desired parameter at the location in the recipe data file and sends the desired parameter to the visual recipe editor for display to the user. Thus the R-DOM object model uses the R-DOM file to locate the desired parameter in the recipe data file.
In further aspects of the invention each type and vendor of semiconductor-manufacturing machine has a different native sequence of parameters in a recipe data file. This requires a different R-DOM file with a different sequence of parameters to map parameter locations in the recipe data file for each type and vendor of semiconductor-manufacturing machine. Thus different R-DOM files are used for different semiconductor-manufacturing machines. The machines have different native sequences of parameters in the recipe data files.
In still further aspects the recipe data files include ASCII formats and binary formats. The ASCII formats include comma-separated-value formats in which records in the recipe data file are delimited by commas. The R-DOM object model counts commas in the recipe data file to locate the desired parameter. The binary formats include fixed-record-length formats where each parameter occupies one or more fixed-length records. The R-DOM object model counts records to locate the desired parameter in the recipe data file. Thus the R-DOM object model locates the desired parameter in recipe data files with binary formats or ASCII formats.
In further aspects, the R-DOM file contains limits for a parameter. The limits indicate maximum and minimum values for a parameter in the recipe data file. However, the recipe data file does not contain the limits but only the parameter""s value. The R-DOM object model further includes a validation means that compares a new value of the desired parameter to the limits and prevents the parameter from being updated to the new value when the new value falls outside the limits. Thus limit checking is performed using the R-DOM file.